Numerical Analysis of Boosting Scheme for Scalable NMR Quantum Computation

Among initialization schemes for ensemble quantum computation beginning at thermal equilibrium, the scheme proposed by Schulman and Vazirani [L. J. Schulman and U. V. Vazirani, in Proceedings of the 31st ACM Symposium on Theory of Computing (STOC'99) (ACM Press, New York, 1999), pp. 322-329] is known for the simple quantum circuit to redistribute the biases (polarizations) of qubits and small time complexity. However, our numerical simulation shows that the number of qubits initialized by the scheme is rather smaller than expected from the von Neumann entropy because of an increase in the sum of the binary entropies of individual qubits, which indicates a growth in the total classical correlation. This result--namely, that there is such a significant growth in the total binary entropy--disagrees with that of their analysis.Comment: 14 pages, 18 figures, RevTeX4, v2,v3: typos corrected, v4: minor changes in PROGRAM 1, conforming it to the actual programs used in the simulation, v5: correction of a typographical error in the inequality sign in PROGRAM 1, v6: this version contains a new section on classical correlations, v7: correction of a wrong use of terminology, v8: Appendix A has been added, v9: published in PR

Design analysis of ductile failure in dovetail connections

The static plastic collapse of ductile dovetail structures is investigated by three analysis methods: slip-line field (SLF) theory based on a sheet drawing model, finite element limit analysis, and linear elastic finite element analysis with adapted pressure vessel design stress linearization and categorization methods. A range of angles and heights are considered in the investigation. Three experimental test cases are also presented. The limit analysis results are found to give the best comparison with the limited experimental results, indicating similar collapse loads and modes of ductile collapse. The SLF solution is found to give conservative but useful failure loads for small dovetail angles but, at angles greater than 30°, the solution is not generally conservative. The pressure vessel design by the analysis stress categorization procedure was adapted for dovetail analysis and was found to give reasonably conservative collapse loads in most cases. However, the procedure requires the designer to consider a number of different stress classification lines to ensure that a conservative collapse load is identified. It is concluded that the finite element limit analysis approach provides the best and most direct route to calculating the allowable load for the joint and is the preferred method when appropriate finite element analysis facilities are available

Community engagement in preparing for natural water disasters of different time and magnitude scales – A comparative study between Japan and England

This exploratory research funded by the Daiwa Anglo-Japanese Foundation considers two chal-lenges recognised in the DRR community in recent years. One is the necessity of ‘all of society engagement’ emphasised in the Sendai Framework for DRR 2015-2030, which has led to the rein-forcement of community-based DRR. The other is, as the Red Cross World Disasters Report 2014 criticises, experts ‘persist’ in prioritising high-impact/low-frequency hazards. Inquiries into communi-ties’ DRR against hazards of different return periods and magnitudes have been scarce. The re-search focuses on natural water disasters, such as floods and typhoons generated due to atmos-pheric forcing factors, which have been intensified by climate change, as well as tsunamis. Both Japan and England have had a series of impacts of them in recent years. Applying a comparative approach, the research discusses four cases of under-researched water disaster-prone communities in Oita and Wakayama Prefectures, and the Essex and Devon Counties. The two research questions probed are: 1) to what extent the perceptions between DRR experts and community members differ in relation to disasters with different return periods and magnitudes; 2) what are the implications of the perception gap on the actualisation of ‘community-based’ and ‘participatory’ DRR. The interdis-ciplinary research team combines the observation of major structural mitigation solutions (e.g. barrier walls, embankments and evacuation shelters etc.) against water disasters of different scales in the four cases, and the analysis of non-structural measures through stakeholder interviews – policy-makers, academics, activists, community members – undertaken in the four communities. One of the key findings of the research is that both DRR experts and community members approach high-im-pact/low-frequency hazards with ‘prevention’ and ‘reduction’ measures, while for low-impact/high-frequency hazards, the countermeasures become ‘adaptation’. This has led us to consider develop-ing a new framework in categorising water disasters, applying a new index – the number of people ‘affected’ – in addition to scale and magnitudes. The novelty of the framework is to include community perspective so as to enable a community-based bottom-up approach in decision-making of DRR measures

Orbital Properties of Sr3Ru2O7 and Related Ruthenates Probed by 17O-NMR

We report a site-separated $^{17}$O-NMR study of the layered perovskite ruthenate Sr$_3$Ru$_2$O$_7$, which exhibits nearly two-dimensional transport properties and itinerant metamagnetism at low temperatures. The local hole occupancies and the spin densities in the oxygen $2p$ orbitals are obtained by means of tight-binding analyses of electric field gradients and anisotropic Knight shifts. These quantities are compared with two other layered perovskite ruthenates: the two-dimensional paramagnet Sr$_2$RuO$_4$ and the three-dimensional ferromagnet SrRuO$_3$. The hole occupancies at the oxygen sites are very large, about one hole per ruthenium atom. This is due to the strong covalent character of the Ru-O bonding in this compound. The magnitude of the hole occupancy might be related to the rotation or tilt of the RuO$_6$ octahedra. The spin densities at the oxygen sites are also large, 20-40% of the bulk susceptibilities, but in contrast to the hole occupancies, the spin densities strongly depend on the dimensionality. This result suggests that the density-of-states at the oxygen sites plays an essential role for the understanding of the complex magnetism found in the layered perovskite ruthenates.Comment: 9 pages, 5 figures, to be published in Phys. Rev.

Uncertain identification

Uncertainty about the choice of identifying assumptions is common in causal studies, but is often ignored in empirical practice. This paper considers uncertainty over models that impose different identifying assumptions, which, in general, leads to a mix of point- and set-identified models. We propose performing inference in the presence of such uncertainty by generalizing Bayesian model averaging. The method considers multiple posteriors for the set-identified models and combines them with a single posterior for models that are either point-identified or that impose non-dogmatic assumptions. The output is a set of posteriors (post-averaging ambiguous belief) that are mixtures of the single posterior and any element of the class of multiple posteriors, with weights equal to the posterior model probabilities. We suggest reporting the range of posterior means and the associated credible region in practice, and provide a simple algorithm to compute them. We establish that the prior model probabilities are updated when the models are "distinguishable" and/or they specify different priors for reduced-form parameters, and characterize the asymptotic behavior of the posterior model probabilities. The method provides a formal framework for conducting sensitivity analysis of empirical findings to the choice of identifying assumptions. In a standard monetary model, for example, we show that, in order to support a negative response of output to a contractionary monetary policy shock, one would need to attach a prior probability greater than 0.32 to the validity of the assumption that prices do not react contemporaneously to such a shock. The method is general and allows for dogmatic and non-dogmatic identifying assumptions, multiple point-identified models, multiple set-identified models, and nested or non-nested models